The present invention relates to a rear projector that displays image on a transmissive screen.
Conventionally, a rear projector that displays a projected and enlarged image on a screen is known as a large-screen display device.
In such rear projector, the light beam from a light source is irradiated on a transmissive liquid crystal panel, where the light beam is modulated in accordance with image information by the transmissive liquid crystal panel, and is enlarged by a projection lens, of which optical path is changed by a reflection mirror to be introduced to a rear side of a screen.
According to the above arrangement, all of the components can be housed in a movable casing and the image on the screen can be viewed in a well-lighted room.
In order to adjust the position of the image displayed on the screen, a position adjuster, which normally adjusts the position of the projection lens in horizontal or vertical position, is necessary for such rear projector. Such mechanism is shown in, for instance, Japanese Patent Laid-Open Publication No. 2001-94905 and Japanese Patent Laid-Open Publication No. 2002-107663.
However, when such simple position adjuster where the position of the projection lens is horizontally or vertically adjusted is used for adjusting the position of the image, there is certain limit capable of adjusting the display position of the image and undisplayable area for displaying the image is formed on the screen even after adjusting the position of the projection lens.
Further, there is difference in the tolerance of the profile of the casing of the rear projector and the tolerance of the component installed in the casing, the tolerance causing difference in aspect ratio of the displayed image, so that the projection dispersion is generated on the image displayed on the screen.
Minute adjustment is required to optimize the projection dispersion. However, since undisplayable area is formed by the conventional divisional display position adjuster, the image cannot be displayed on the entire screen and, when large undisplayable area is formed, the displayed image runs off the edge of the screen and only the image displayed within the frame of the screen can be recognized by a viewer.